Lithograph with a trigger mask and method of producing digital holograms in a storage medium

ABSTRACT

A lithograph for producing digital holograms in a storage medium includes a light source for producing a write beam, the light source having drive means for the two-dimensional movement of the write beam relative to the storage medium and having a first objective for focusing the write beam onto the storage medium. Writing computer-generated holograms by means of optical lithography is solved in that: a two-dimensional trigger matrix is provided, means of producing a scanning beam are provided, a second objective for focusing the scanning beam onto the trigger matrix is provided, the drive means moves the scanning beam two-dimensionally relative to the surface of the trigger matrix, the movement of the scanning beam being coupled with the movement of the write beam, and means for generating a trigger signal to control the intensity of the write beam are connected to the trigger matrix.

BACKGROUND OF THE INVENTION

The present invention relates to a lithograph for producing digitalholograms in a storage medium. In particular, the lithograph has a lightsource for producing a write beam, drive means for the two-dimensionalmovement of the write beam relative to the storage medium and a firstobjective for focusing the write beam onto the storage medium to bewritten. Furthermore, the invention relates to a method of producingdigital holograms in a storage medium.

Digital holograms are two-dimensional holograms which consist ofindividual points with different optical properties and from which, whenilluminated with a coherent electromagnetic wave, in particular a lightwave, images and/or data are reproduced by means of diffraction intransmission or reflection. The different optical properties of theindividual points can be reflective material properties, for example asa result of surface topography, varying optical path lengths in thematerial of the storage medium (refractive indices) or color values ofthe material.

The optical properties of the individual points are calculated by acomputer, and this thus involves what are known as computer-generatedholograms (CGH). With the aid of the focused write beam, during thewriting of the hologram the individual points of the hologram arewritten into the material, the focus being located in the region of thesurface or in the material of the storage medium. In the region of thefocus, focusing has the effect of a small area of action on the materialof the storage medium, so that a large number of points of the hologramcan be written on a small area. The optical property of the respectivelywritten point in this case depends on the intensity of the write beam.For this purpose, the write beam is scanned in two dimensions over thesurface of the storage medium with varying intensity. The modulation ofthe intensity of the write beam is in this case carried out either viainternal modulation of the light source, for example a laser diode, orvia external modulation of a write beam outside the light source, forexample with the aid of optoelectronic elements. Furthermore, the lightsource can be formed as a pulsed laser whose pulse lengths can becontrolled, so that control of the intensity of the write beam can becarried out by the pulse lengths.

As a result of the scanning of the intensity-modulated write beam, anarea with an irregular point distribution is thus produced, the digitalhologram. This can be used to identify and individualize any desiredobjects.

Scanning lithographic systems are intrinsically widespread. For example,scanning optical systems are incorporated in conventional laserprinters. However, these systems cannot be used for the production ofholograms, since the requirements for this intended application differconsiderably from those in laser printers. In the case of good printingsystems, the resolution is around 2500 dpi while, in the production ofholograms, a resolution of about 25 000 dpi is required. In addition, indigital holography, only comparatively small areas are written. Theseare, for example, 1 to 5 mm², other sizes also being possible. Theaccuracy of the write pattern in the case of a lithograph for theproduction of digital holograms of, for example, 1000×1000 points on anarea of 1×1 mm² must be about ±0.1 μm in both orthogonal directions.Furthermore, the writing speed should be about 1 Mpixel/s, in order thatin each case a hologram can be written in a time of about 1 s. Theaforementioned magnitudes are exemplary and do not constitute anyrestriction of the invention.

Digital holograms can be produced by means of conventional scanningmethods, with which the angle of the incident beam is varied bystationary optics. For example, scanning mirror lithographs withgalvanometer and/or polygonal scanners operate on this principle.

In all the scanning methods known hitherto, one disadvantage is that nocontrol of the accurate positioning of the write beam is possible whichis capable of maintaining a predefined point pattern of the digitalhologram at the writing speeds to be achieved.

SUMMARY OF THE INVENTION

The present invention is therefore based on the technical problem ofwriting computer-generated holograms by means of optical lithography asquickly as possible and with little effort with simultaneous accuratecontrol of the positioning of the write beam.

According to a first teaching of the invention, the technical problemindicated previously is solved by a method having the features of claim1. This is a method in which a write beam is focused onto the storagemedium and moved two-dimensionally relative to the storage medium, inwhich a scanning beam is focused onto a trigger matrix having aplurality of pixels and moved two-dimensionally relative to the triggermatrix, the movement of the scanning beam being coupled with themovement of the write beam, in which, when the scanning beam strikes apixel belonging to the trigger matrix, a position trigger signal isgenerated, in which, with the aid of the position trigger signal, thewrite beam is activated and, at the position associated with the pixelbelonging to the trigger matrix, a point of the digital hologram isproduced on the storage medium, and in which the hologram is written byintroducing radiation energy point by point, the intensity of the writebeam being controlled as a function of the position of the write beam onthe storage medium.

According to the invention, it has been recognized that exactpositioning of the write beam can be carried out if the write beam istriggered exactly when it is located at the predefined position. Sincedirect observation of the storage medium for monitoring the position ofthe write beam is ruled out, according to the invention, with the aid ofa scanning beam whose movement is coupled with the movement of the writebeam, a trigger matrix is scanned, using which position trigger signalsare generated to control the intensity of the write beam.

In other words, outside the region of the storage medium actually to bewritten, the two-dimensional movement is registered and evaluated forposition control of the write beam. The position control signaltherefore constitutes time control with which the write beam can beintensity-controlled during its continuous scanning movement.

The scanning beam is preferably moved in a predefined movementrelationship with the write beam. Thus, the scanning beam can scan atrigger matrix whose area is greater than the region of the storagemedium to be written. If the trigger matrix is, for example, 10 timeslarger than the hologram to be produced, then the movement of thescanning beam is enlarged in the ratio 10:1 in proportion to themovement of the write beam. If, therefore, for example a hologram withan area of 1×1 mm² is to be written, the scanning beam scans a triggermatrix with an area of 10×10 mm².

Therefore, optoelectronic array detectors whose pixel resolution lies inthe region of 10 μm can advantageously be used as trigger matrices inorder to write a point pattern of the hologram with 1 μm resolution.

For this purpose, the scanning beam is preferably further focused onto asize which corresponds at most to the pixel dimension of the triggermatrix. Triggering then takes place only under the condition that theintensity of the scanning beam registered by the relevant pixel isgreater than a predefined multiple of the intensities registered by theadjacent pixels. This ensures that the scanning beam strikes the pixelof the trigger matrix within a predefined inaccuracy. It thus becomespossible to maintain the point pattern of the hologram to be writtenwith an accuracy of, for example, at most 10% deviation from thepredefined point pattern.

In a further refinement of the present invention, for each pixel anintensity value of the write beam is assigned to the trigger matrix andthe intensity of the write beam is controlled with the associatedintensity value during the generation of the position trigger signalassigned to a pixel. Thus, the generation of the position trigger signalis simultaneously linked with an intensity value, in order to set theintensity of the write beam.

If the trigger matrix is formed, for example, using CMOS technology,each pixel can be connected to a storage element arranged in the CMOSchip. During the generation of the trigger signal, the associatedstorage element is then automatically read and transmitted together tothe control of the intensity of the write beam. In this way, a fast“intelligent” trigger matrix is achieved, whose high reaction speedpermits triggering of the write beam in the region of 1 Mpixel/s.

In addition, a CMOS detector or a CCD array can be linked with a faststorage element in order, following the generation of the trigger signalby means of the CMOS or CCD array, to determine the associated intensityvalue via the storage element and transmit it to the intensity controlof the write beam within the predefined transmission time.

In a further preferred embodiment, within the writing operation of adigital hologram with each pixel of the trigger matrix, a positiontrigger signal is generated at most only once. This ensures that thewrite beam does not write the same point of the digital hologramrepeatedly during the writing operation. Double or multiple exposuresare effectively avoided as a result if a point is scanned repeatedly.This has in particular the advantage that the holograms, in spite of thehigh resolution, can be written reliably even under rough ambientconditions. For example, the influence of vibrations is reduced.

In particular, it is recommended that the hologram area and the triggermatrix are scanned freely by the write beam and by the scanning beam ata predefined multiple rate, also called oversampling. Thetwo-dimensional scanning movement of the write beam is therefore notsubject to any predefined guidance. The multiple scanning during thewriting operation in this case ensures that a large part orsubstantially all of the points of the hologram are scanned.

For the functionality of the hologram, it is not neccesary for all thepoints to be written. Of course, however, the quality of the hologram isbetter the more points of the digital pattern have been written. Inaddition, the free scanning of the write and scanning beams ensuresgreater robustness of the writing operation.

According to a second teaching of the present invention, the technicalproblem indicated above is solved by a lithograph having the features ofclaim 9.

The previously described functioning of the present invention and itspreferred configurations can also advantageously be used in a scanning,in particular confocal, microscope. In a microscope of this type, thesurface to be examined is scanned or observed with a light beam and thereflected light intensity is measured. During the scanning of thesurface, the image is then assembled from the measured intensities ofthe reflected light. The surface is therefore scanned in a pattern, ashas been described previously.

In the present case, for this purpose a beam splitter is arranged in thebeam path of the reflected beam, in front of or preferably behind theobjective, in order to lead the reflected radiation to an opticalsensor. The latter measures the reflected intensity.

With a microscope of this type, the technical problem of observing orscanning a surface as quickly as possible and with little effort issolved. This is in accordance with the technical problem on which thelithograph previously described is based. The advantages previouslydescribed for the lithograph are likewise achieved in a microscope ofthis type.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following text, the invention will be explained in more detailusing exemplary embodiments and with reference to the appended drawing,in which:

FIG. 1 shows a first exemplary embodiment of a lithograph according tothe invention,

FIG. 2 shows a second exemplary embodiment of a lithograph according tothe invention,

FIG. 3 shows a third exemplary embodiment of a lithograph according tothe invention in a plan view,

FIG. 4 shows the lithograph shown in FIG. 3 in a side view,

FIG. 5 shows a fourth exemplary embodiment of a lithograph according tothe invention in a plan view,

FIG. 6 shows the lithograph shown in FIG. 5 in a side view and

FIG. 7 shows a microscope according to the invention with a structurewhich corresponds substantially to the structure of the lithographillustrated in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a first exemplary embodiment of a lithograph 2 according tothe invention for producing digital holograms in a storage medium 4which is arranged on a carrier 6. A light source 8 for producing a writebeam 10 preferably has a laser or a laser diode, so that the write beam10 is formed as a laser beam.

The lithograph 2 also has drive means for the two-dimensional movementof the write beam 10 relative to the storage medium 4, which are formedas galvanometrically driven scanning mirrors 12 and 14 and deflect thewrite beam in two x and y directions arranged substantially orthogonallyto each other. The x direction runs, for example, in the plane of FIG. 1and the y direction runs in a plane at right angles to the plane of theFigure. The mirrors 12 and 14 therefore constitute an x/y scanningmirror arrangement. Instead of one of the two or both galvanometricscanning mirrors, rotatable polygonal mirrors can also be used.

Optionally, a beam spreader or collimator 15 is also arranged in thebeam path, behind the scanning mirrors 12 and 14, in order to produce awidened write beam 10.

A first objective 16 focuses the write beam 10 onto the storage medium 4to be written, so that, at the focus 17, depending on the focusedintensity of the write beam 10, the optical property of the storagemedium 4 is changed or remains unchanged.

According to the invention, a two-dimensional trigger matrix 18 isprovided, onto which a scanning beam 22 coupled out of the write beam 10by a beam splitter 20 is focused at a focus 25 by a second objective 24.

The two objectives 16 and 24 in each case have three lenses of afocusing lens system. However, the precise configuration of theobjectives 16 and 24 is unimportant. However, the objectives 16 and 24must ensure that their angular deflections in the x/y direction dependlinearly on each other, since otherwise there is no coupling between themovements of the foci 17 and 25.

As emerges from the structure of the lithograph 2 according to FIG. 1,the drive means, that is to say the scanning mirrors 12 and 14, move notonly the write beam 10 but also the scanning beam 22. This is becausethe beam splitter 20 is arranged behind the scanning mirrors 12 and 14in the beam path of the write beam 10. Thus, the scanning beam 22 ismoved two-dimensionally in the same way as the write beam 10, so thatthe scanning beam 22 is moved relative to the surface of the triggermatrix 18. This results in the movement of the scanning beam 22 beingcoupled with the movement of the write beam 10.

Furthermore, control means 26 are connected via a line 28 to the triggermatrix 18, in order to transmit a trigger signal to the light source 8via a line 30 in order to control the intensity of the write beam 10.The control means 26 can in this case be formed as a fast storage chipor as a computer. By means of the signal transmitted via the line 30,the write beam 10 is modulated as a function of the position of thefocus 25 of the scanning beam 22 on the trigger matrix 18, which iscoupled to the position of the focus 17 of the write beam 10 on thestorage medium 4.

In other words, the write beam 10 is set to write hologram points withtwo or more different intensity values. In the case of binary writing,the intensity is switched to and fro between two different values,depending on whether a point is to be written or not. Likewise, writinghologram points with a gray value graduation is possible and practical.In order to register the focus 25 on the trigger matrix 18, however, itis necessary for the lower or lowest intensity value of the write beam10 not to be equal to zero, since the scanning beam 22 is coupled out aspart of the write beam 10.

Furthermore, in the case of the structure of the lithograph 2illustrated in FIG. 1, a length-related step-up ratio between themovement of the write beam 10 on the storage medium 4 and of thescanning beam 22 on the trigger matrix 18 is predefined. This isimplemented by means of different focal lengths of the two objectives 14and 26. If, for example, the focal length of the first objective 16 issmaller by a factor 10 than the focal length of the second objective 24,then the movement of the focus 25 of the scanning beam 22 on the triggermatrix 18 is greater by the same factor 10 times than the movement ofthe focus 17 on the surface of the storage medium 4. In FIG. 1, only afocal length ratio of about 2 is illustrated, for reasons of space.However, this illustrates that a specific ratio is unimportant in thepresent configuration of the invention.

In FIG. 2, a second exemplary embodiment of a lithograph 2′ according tothe invention is illustrated which, in many constituent parts, coincideswith the exemplary embodiment illustrated in FIG. 1. Therefore,identical constituent parts with identical designations are used.

As distinct from the first exemplary embodiment, the scanning beam 22′is not coupled out as part of the write beam 10. Instead, a second lightsource 32 produces the scanning beam 22′, which is coupled into the beampath of the write beam 10 in front of the first scanning mirror 12 by abeam splitter 34. The scanning beam 22′ has a wavelength or polarizationwhich differs from the write beam 10, so that the beam splitter 34 isformed as a dichroic or polarizing beam splitter. The beam splitter 20is then correspondingly formed so as to be dichroic or polarizing, inorder to couple the scanning beam 22′ out of the common beam path.

The scanning beam 22′ is therefore independent of the intensitymodulation of the write beam 10, so that the latter can also be switchedoff, that is to say set with an intensity equal to zero.

Since, otherwise, the functioning of the exemplary embodimentillustrated in FIG. 2 is identical to the first exemplary embodiment,reference is made to the description given above.

A third exemplary embodiment of a lithograph 2″ according to theinvention is illustrated in FIGS. 3 and 4. The structure of thelithograph 2″ is fundamentally different from the structure illustratedin FIGS. 1 and 2. This is because, in the lithograph 2″, the write beamand the scanning beam are not moved with the objectives at rest but thetwo-dimensional movement of the focal points is carried out bydisplacing the objectives, while the write beam and the scanning beamrun substantially three-dimensionally constantly in front of theobjectives.

As FIGS. 3 and 4 show, the first objective is formed as a writing lens40 and the second objective as a scanning lens 42, which are fixed to acommon holding arm 44. The holding arm 44 is mounted such that it canrotate about an axis of rotation 46.

The write beam 10, shown by dashed lines, is produced in a mannerpreviously described with the aid of a light source, which is notillustrated in detail in FIGS. 3 and 4. The write beam 10 has a diameterwhich is greater than the aperture of the writing lens 40. The writinglens 40 therefore focuses only part of the scanning beam 10. The writinglens 40 can therefore be moved within the region occupied by the writebeam without different illumination of the writing lens 40 occurring. Asa result, assuming a uniform intensity distribution within the profileof the write beam 10, an identical intensity at the focus 17 is ensured.

The scanning beam 22 is supplied to the scanning lens 42 with the aid ofa fiber 47, the light source for producing the scanning beam 22 notbeing illustrated in FIGS. 3 and 4. The scanning lens 42 focuses thescanning beam 22 coupled out of the fiber 47 at the focus 25 on thesurface of the trigger matrix 18.

A first drive device in the form of a quasi-linear linear motor 48produces an oscillating rotational movement of the holding arm 44. Forthis purpose, the linear motor 48 has a stator 50 connected to theholding arm and magnetic coil arrangements 52 and 54 arranged aboveand/or below said stator. This arrangement is known per se from theprior art of the read head drives for computer hard disks. In any case,by means of such a linear motor 48, because of the low mass and thepowerful drive, an oscillatory movement of the holding arm 44 in therange from 5-10 kHz can be produced.

By means of the linear motor 48, a lateral arcuate movement of thewriting lens 40 and the scanning lens 42 is produced, which can besuperimposed with a further movement, extending substantiallytransversely thereto, to form a two-dimensionally scanning movement. Asa result, scanning of the region of the storage medium 4 to be writtenand of the trigger matrix 18 by the foci 17 and 25 is made possible.

Furthermore, FIGS. 3 and 4 illustrate the fact that the writing lens 40is arranged at a first distance from the axis of rotation 46 of theholding arm 44, and the scanning lens 42 is arranged at a seconddistance from the axis of rotation 46, the second distance being greaterthan the first distance. Therefore, during the lateral arcuate movementof the two lenses 40 and 42, there is a step up in the movement in theratio in which the lenses 40 and 42 are spaced apart from the axis ofrotation 44. In this case, it is preferred for the distance of thescanning lens 42 to be greater by the factor 10 than the distance of thewriting lens 40 from the axis of rotation 46. This corresponds to thenumerical example specified above. The two lateral arcuate movements areidentified by the double arrows A1 and A2 in FIG. 3.

The writing lens 40 and the scanning lens 42 are arranged on the holdingarm 44 on opposite sides of the axis of rotation 46. This makes itpossible to arrange the entire structure of the holding arm 44 and thedrive 48, as well as a lever mechanism 56 described below, in a housing58, while the writing lens 40 is arranged outside the housing 58. As aresult, supplying the storage medium 4 underneath the writing lens 40 issimplified. In addition, the scanning of the trigger matrix 18 isshielded from the surroundings, so that an exact relative movement canbe implemented without relatively great influences from outside.

The movement transverse to the lateral arcuate movement is produced by asecond drive device for producing a linear movement of the triggermatrix 18 and of the rotary bearing 46 of the holding arm 44 relative tothe storage medium 4. The drive itself is not illustrated, but, via alever arrangement 56 illustrated schematically, both the trigger matrix18 and a housing 58 surrounding the arrangement of the holding arm 44and linear drive 48 can be displaced linearly with respect to a base 60.Since the attachment points of the lever 56 to the trigger matrix 18 andto the housing 58 are arranged at different distances from the pivotconnected to the base 60, a step-up, predefined as a result of thedifferent distances, of the movement of the holding arm 44 and of thetrigger matrix 18, that is to say of the foci 17 and 25, takes place.The different large linear movements are illustrated by the doublearrows B1 and B2 in FIG. 4. Instead of the lever mechanism illustratedschematically, slip-free geared transmissions or hydropneumatictransmissions known per se can be used.

The situation is thus achieved where the second drive means implement amechanical step up, which has the effect of a movement ratio between themovement of the trigger matrix 18 and of the rotary bearing 46 of theholding arm 44 relative to the storage medium 4.

FIGS. 5 and 6 show a fourth exemplary embodiment of a lithograph 2′″according to the invention which, in principle, corresponds to theexemplary embodiment illustrated in FIGS. 3 and 4. Therefore, identicaldesignations designate coincident constituent parts here, too. Only thefeatures differing from the third exemplary embodiment will also beexplained here.

The second objective, that is to say the scanning lens 42, focuses partof the widened scanning beam 22 onto the surface of the trigger matrix18. The scanning beam 22 is therefore not guided via a fiber but isaimed freely onto the region of the trigger matrix 18. The scanning lens42 therefore focuses part of the scanning beam 22 onto the triggermatrix 18. Since the intensity at the focus is considerably higher thanin the unfocused scanning beam 22, the trigger matrix 18 does not needto be shielded. This has the advantage that the mass to be moved of theholding arm 44 is not increased by an additional shield arranged in theregion of the scanning lens 42.

Furthermore, in the exemplary embodiment illustrated in FIGS. 5 and 6,the two lenses 40 and 42 are fixed to the holding arm 44 on the sameside of the axis of rotation 46.

In all the exemplary embodiments of the lithograph according to theinvention, a trigger matrix 18 is provided whose properties maygenerally be presented as follows. The trigger matrix 18 is acommercially available optoelectronic component, for example formed as aCMOS chip or as a CCD chip, and has a plurality of pixels. These arearranged in a pattern, in particular an orthogonal pattern.

If a pixel is illuminated with a sufficient intensity, this pixelgenerates a position trigger signal, which is passed on to the controlmeans 26 via the line 28 illustrated only in FIGS. 1 and 2. There, anevaluation of the trigger signal in accordance with the position data iscarried out and a corresponding control signal is transmitted to thelight source 8 for the purpose of modulating the intensity of the writebeam 10.

On its light-sensitive surface, a CMOS chip has a matrix in a pattern of10 m spacing between the individual pixels, which are separated from oneanother by “blind” lands or gaps. The lands are formed in such a waythat, in conjunction with a threshold value and the beam profile of thefocus 25 of the scanning beam 22, the accuracy requirements on thetrigger location are met.

Furthermore, the control means 26 for generating a trigger signal canhave storage means which are connected to the pixels of the triggermatrix. In the storage means, intensity values relating to all the x/ypositions are stored and, upon the appropriate position trigger signalfrom the trigger matrix 18, are read out and transmitted concomitantlyto the control of the light source 8. In the case of a CMOS chip, thestorage means can be arranged integrated directly in the chip with thepixels. These then correspond to “intelligent” pixels.

A further feature of the previously described configurations of thelithograph is that the distance between the storage medium 4 and theobjective 16 in FIGS. 1 and 2 and the writing lens 40 in FIGS. 4 and 6can be adjusted variably. This is identified by a double arrowdesignated “Z”. For an adjustment of the distance in the z direction,means not illustrated in the Figures are provided. These can be anylinear adjusting means which can be driven by motor or by hand. By meansof adjusting the distance, the position of the focus in the storagemedium 4 can be arranged at various depths, and likewise adjustment ofthe focus in the case of storage media 4 of different thicknesses ispossible. Finally, at least two digital holograms can be written atdifferent levels within the storage medium 4, in order to produce whatare known as multilayer holograms.

FIG. 7 illustrates a microscope according to the invention which, in itsstructure, corresponds to the lithograph illustrated in FIG. 1.Therefore, identical designations designate identical components tothose as have been described in connection with FIG. 1, even if, indetail, other designations are used which identify the differencebetween writing and observing.

In addition to the structure illustrated in FIG. 1, a deflection plane70 is arranged in the beam path of the light reflected from the surface,behind, that is to say above, the objective 16. This can be implementedby means of a semitransparent mirror or a beam splitter and has noinfluence or only an insignificant influence on the observation beam.

The deflection plane 70 deflects the reflected beam laterally, to theleft in FIG. 7, so that it strikes a photosensor 72 which measures theintensity of the reflected light.

By varying the observation beam 10 relative to the object 4 to be viewedunder the microscope, the surface is then scanned and the reflectancemeasured point by point. An image of the scanned surface can thus beassembled.

If, then, the light beam emitted by the light source 8, which can bedesignated an observation beam in the microscope, is produced with asubstantially identical intensity, then the measured intensity of thereflected beam is a measure of the reflectance of the scanned surface.

1. A method of producing digital holograms in a storage medium, whereina write beam is focused onto the storage medium and movedtwo-dimensionally relative to the storage medium, a scanning beam isfocused onto a trigger matrix having a plurality of pixels and movedtwo-dimensionally relative to the trigger matrix, the movement of thescanning beam being coupled with the movement of the write beam, whenthe scanning beam strikes a pixel belonging to the trigger matrix, aposition trigger signal is generated, with the aid of the positiontrigger signal and an intensity value assigned to the pixel of thetrigger matrix, the write beam is activated and, at the positionassociated with the pixel belonging to the trigger matrix, a point ofthe digital hologram is produced on the storage medium, and the hologramis written by introducing radiation energy point by point, the intensityof the write beam being controlled as a function of the position of thewrite beam on the storage medium, wherein the scanning beam is coupledout so it is never incident upon the storage medium.
 2. The method as inclaim 1, wherein the scanning beam is moved in a predefined movementrelationship with the write beam.
 3. The method as in claim 1, whereinthe scanning beam is focused to a size which corresponds at most to thepixel dimension of the trigger matrix.
 4. The method as in claim 3,wherein a trigger signal is generated when the intensity of the scanningbeam registered by the relevant pixel is greater than a given multipleof the intensities respectively registered by the adjacent pixels. 5.The method as in claim 1, wherein for each pixel, an intensity value ofthe write beam is assigned to the trigger matrix, and in which theintensity of the write beam is controlled with the associated intensityvalue during the generation of the position trigger signal assigned to apixel.
 6. The method as in claim 1, wherein within the writing operationof a digital hologram with each pixel of the trigger matrix, a positiontrigger signal is generated at most only once.
 7. The method in claim 6,wherein the hologram area and the trigger matrix are scanned freely bythe write beam and by the scanning beam at a predefined multiple rate.8. The method as claimed in claim 1, wherein the distance between theobjective or writing lens and the storage medium is adjusted for writingat different depths within the storage medium.
 9. The lithograph forproducing digital holograms in a storage medium, in particular forimplementing a method as in claim 1, having a light source for producinga write beam, having drive means for the two-dimensional movement of thewrite beam relative to the storage medium and having a first objectivefor focusing the write beam onto the storage medium to be written,wherein a two-dimensional trigger matrix is provided, means of producinga scanning beam are provided, a second objective for focusing thescanning beam onto the trigger matrix is provided, the drive means movethe scanning beam two-dimensionally relative to the surface of thetrigger matrix, the movement of the scanning beam being coupled with themovement of the write beam, and control means for assigning intensityvalues to the pixels of the trigger matrix and for generating a triggersignal to control the intensity of the write beam are connected to thetrigger matrix, wherein the scanning beam is coupled out so it is neverincident upon the storage medium.
 10. The lithograph as in claim 9,wherein a length-based step-up ratio between the movement of thescanning beam on the trigger matrix and of the write beam on the storagemedium is predefined.
 11. The lithograph as in claim 9, wherein thedrive means are formed as an x/y scanning mirror arrangement for movingthe write beam; and the means of producing the scanning beam have meansfor coupling part of the write beam out as a scanning beam in the beampath of the write beam behind the drive means.
 12. The lithograph asclaimed in claim 11, wherein the means of producing the scanning beam;have a second light source for producing a scanning beam with awavelength or polarization differing from the write beam; input couplingmeans for coupling the scanning beam into the beam path of the writebeam in front of the drive means; and the output coupling means coupleout the scanning beam.
 13. The lithograph as in claim 11, wherein thefocal length of the second objective is greater by a predefined factorthan the focal length of the first objective.
 14. The lithograph as inclaim 9, wherein the trigger matrix has a plurality of pixels.
 15. Thelithograph as in claim 14, wherein the pixels are arranged in a pattern,in particular an orthogonal pattern.
 16. The lithograph as in claim 14,wherein the trigger matrix is formed as an optoelectronic converter, inparticular as a CCD chip or as a CMOS chip.
 17. The lithograph as inclaim 9, wherein the control means for generating a trigger signal havestorage means which are connected to the pixels of the trigger matrix.18. The lithograph as in claim 9, wherein means are provided foradjusting the distance between the storage medium and the objective orthe writing lens.
 19. A lithograph in claim 9, wherein the lithograph isa microscope.
 20. A lithograph for producing digital holograms in astorage medium, the lithograph comprising: a light source for producinga write beam; a drive means for the two-dimensional movement of thewrite beam relative to the storage medium; and a first objective forfocusing the write beam onto the storage medium to be written; wherein:a two-dimensional trigger matrix is provided; means of producing ascanning beam are provided; a second objective for focusing the scanningbeam onto the trigger matrix is provided; the drive means move thescanning beam two-dimensionally relative to the surface of the triggermatrix, the movement of the scanning beam being coupled with themovement of the write beam; control means for generating a triggersignal to control the intensity of the write beam are connected to thetrigger matrix; the first objective and the second objective are fixedto a rotatably mounted holding arm; a first drive device for producingan oscillating rotational movement of the holding arm is provided; asecond drive device for producing a linear movement of the triggermatrix and of the rotary bearing of the holding arm relative to thestorage medium is provided; and the write beam illuminating the firstobjective completely within its movement range, wherein the scanningbeams is coupled out so it is never incident upon the storage medium.21. The lithograph as in claim 20, wherein a fiber is connected to thesecond objective in order to supply the scanning beam.
 22. Thelithograph as in claim 20, wherein the second objective focuses part ofthe widened scanning beam onto the surface of the trigger matrix. 23.The lithograph as in claim 20, wherein the first objective is arrangedat a first distance from the axis of rotation of the holding arm, andthe second objective is arranged at a second distance from the axis ofrotation, the second distance being greater than the first distance. 24.The lithograph as in claim 23, wherein the first objective and thesecond objective are arranged on the holding arm on opposite sides ofthe axis of rotation.
 25. The lithograph as in claim 20, wherein thesecond drive means have a mechanical step up which bring about amovement ratio between the movement of the trigger matrix and of therotary bearing of the holding arm relative to the storage medium.
 26. Amicroscope for scanning an object, having a light source for producingan observation beam, having drive means for the two-dimensional movementof the observation beam relative to the object, and having a firstobjective for focusing the observation beam onto the object, wherein atwo-dimensional trigger matrix is provided, means of producing ascanning beam are provided, a second objective for focusing the scanningbeam onto the trigger matrix is provided, the drive means move thescanning beam two-dimensionally relative to the surface of the triggermatrix, the movement of the scanning beam being coupled with themovement of the observation beam, wherein the scanning beams is coupledout so it is never incident upon the storage medium.